Field of the Invention
Embodiments of the present invention relate to a display apparatus, and particularly, to an In-Cell touch screen and a display apparatus.
Description of the Related Art
With rapid development of display technology, a touch screen (Touch Screen Panel) has been widely used in people' life. Currently, the touch screen may be classified, according to configurations thereof, an Add-on mode touch screen (Add-on Mode Touch Panel), On-Cell touch screen (On-Cell Touch Panel), and In-Cell touch screen (In-Cell Touch Panel). The Add-on mode touch screen is formed by separately manufacturing a touch screen and a liquid crystal display (LCD) screen and then joining the touch screen and the liquid crystal display (LCD) screen together to make a liquid crystal display (LCD) screen having a touch function. The Add-on mode touch screen has disadvantages such as a high manufacturing cost, a lower light transmittance, a larger thickness for an assembled module, and the like. For an In-Cell touch screen, a touch electrode of the touch screen is embedded inside the liquid crystal display screen, which not only reduces the entire thickness of the assembled module, but also greatly reduces manufacturing cost of the touch screen. Thus, an In-Cell touch screen has become popular in various panel manufacturers.
Presently, an existing capacitance type In-Cell touch screen is implemented by adding touch scan lines and touch sensing lines directly on an existing TFT (Thin Film Transistor) array substrate. That is, two layers of strip electrodes are manufactured, on a surface of the TFT array substrate. The two layers of strip electrodes are located in different planes and the strip electrodes in the two layers intersect with each other and serve as the touch drive lines and touch sensing lines of the touch screen respectively. A mutual capacitance is formed at an intersection between two strip electrodes located in different planes. Operational principle of the capacitance type In-Cell touch screen is described as follows: while a driving signal is applied to an electrode used as the touch drive line, a voltage signal of the touch sensing line induced by the mutual capacitance is detected. During this period, when a human body contacts the touch screen, a body electric field will act on the mutual capacitance and a capacitance value of the mutual capacitance will change and thus the induced voltage signal on the touch sensing line will change. Therefore, a touch position can be determined according to a change of the voltage signal on the touch sensing line.
With the above configuration of the capacitance type In-Cell touch screen, it is required to add new film layers on the existing TFT array substrate, and thus new manufacturing processes are required when the TFT array substrate is manufactured. Therefore the manufacturing cost is increased and the production efficiency is reduced. Moreover, with the above configuration of the capacitance type In-Cell touch screen, the touch scan lines and touch sensing lines are typically made of indium tin oxide (ITO), the light transmittance of the ITO, however, is only 60-80%. Thus, this touch technology is not adapted to be used in a high resolution product.